Mudflow Collapses Bridges in Angeles City

T.J. Casadevall U.S. Geological Survey

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Aerial view of the Abacan River channel as it passes through Angeles City near Clark Air Base on August 12. A mudflow has caused the collapse of main bridges across the Abacan River. Note makeshift bridges for pedestrians. On August 20, mudflows five meters high traveled down ten rivers damaging more than 9,000 houses and three bridges, and killing 31 people.

Mount Pinatubo is an andesitic island arc volcano, located on the southwestern part of the island of Luzon in the Philippines. Prior to 1991, it had been dormant for more than 635 years. After months of rumbling, the volcano stirred to life on April 2, 1991. The next two and a half months were marked by generally increasing volcanic and seismic activity at the site. On June 15, a cataclysmic eruption began with a tremendous explosion. This slide set shows the early stages of the eruption phase, the cataclysmic eruption of June 15, and the effects and aftermath of the eruption. Subsequent calamities caused by the ash, pyroclastic flows, mud flows, and flooding are also depicted.